Structure for fixing the current supply assembly in the rotor of electric machines

ABSTRACT

A structure for fixing the current-supply assembly in the rotor of an electric machine, such as a turbogenerator and for insuring high reliability of the current supply assembly. The device insures high mechanical strength of the supply assembly as well as satisfactory electric contact. The current-supply assembly comprises a rotor shaft whose central hole accommodates currentconducting bars; a bushing fitted on the rotor shaft and sliprings fitted on the bushing and electrically insulated therefrom; current-conducting screws making electrical connection between buses coupled to the sliprings and the current-conducting bars, said current-conducting screws and buses being also insulated from the rotor shaft and the bushing to which they are fixed with the help of keys disposed in the axial and transverse slots provided in the bushing.

United States Patent Karpman et al.

[54] STRUCTURE FOR FIXING THE CURRENT SUPPLY ASSEMBLY IN THE ROTOR OF ELECTRIC MACHINES [22] Filed: Apr. 27, I970 '[21] Appl.No.: 29,755

Related U.S. Application Data 1 [63] Continuation of Ser. No. 751,567, Aug. 9, l968,abandoned.

[52] U.S. Cl ..3l0/231, 310/261 [51] Int. Cl. ..H02k 13/00 [58] Field ofSearch 10/23 l235,261,

v IMO/263,270, 264, 219, 229

[56] Reterences Cited Y UNITED STATES PATENTS pi m "am/235' 1 1 Feb. 1,1972

3,023,331 2/1962 Hoffman et al. ..310/232 344,542 6/1886 Parsons .310/270 X 1,870,236 8/ 1932 CherrenluL. 10/232 3,290,527 12/ 1966 Haberman ..310/233 2,322,01 1 6/1943 French ..310/232 FOREIGN PATENTS OR APPLICATIONS 699,566 1 H1940 Germany ....3 10/261 891,994 3/1962 GreatBritain ..3l0/232 Primary Examiner-D. F. Duggan Assistant Examiner B. A. Reynolds Attorney-Waters, Roditi, Schwartz & Nissen [57] ABSTRACT A structure for fixing the current-supply assembly in the rotor of an electric machine, such as a turbogenerator and for insuring high reliability of the current supply assembly. The device insures high mechanical strength of the supply assembly as well as satisfactory electric contact. The current-supply assembly comprises a rotor shaft whose central hole accommodates current-conducting bars; a bushing fitted on the rotor shaft and sliprings fitted on the bushing and electrically insulated therefrom; current-conducting screws making electrical connection between buses coupled to the sliprings and the I current conducting'bars, said current-conducting screws and 1 buses being also insulated from the rotor shaft and the bushing to which they are fixed with the help of keys disposed in the axial and transverse'slots provided in the bushing.

PATENTED FEB 1 I972 SHEET 1 OF 5 PATENTED FEB 1 I972 SHEET 8 0F 5 1 STRUCTURE FOR FIXING THE CURRENT SUPPLY ASSEMBLY IN THE ROTOR OF ELECTRIC MACHINES This application is a continuation of application Ser. No. 75 L567, filed Aug. 9, I968, since abandoned.

The present invention relates to the electric machine engineering and, more particularly, to the rotors of turbogenerators and other large high-speed electric machines.

Known in the art are rotors of electric machines, and in particular, of turbogenerators, current supply to exciting winding of which'is accomplished by buses arranged inside the central hole of the rotor shaft and fixed in the region of the sliprings by means of keys seated in the axial grooves of the cylindrical bush fitted on the shaft.

Disadvantages of such a design are the necessity of increasing the axial length of the rotor in order to accommodate the lead-fixing keys of current supply leads, the difficulty of assembling the rotor and the additional vibration due to the first disadvantage.

A primary object of the present invention is to eliminate the above-mentioned disadvantages.

A further object is to bring the current supply leads into the rotor in such a manner as to ensure a reliable electric contact, reduce the vibration of the sliprings and provide an adequate fixing of the current supply assembly. I

In accordance with the present invention these objects are attained by fitting rotors of known types with a cylindrical bush having transverse slots that intersect with the axial slots of the same bush.

Such a design of the rotor of electrical machines allows to reduce the axial dimensions of the current supply assembly, fix the current supply leads securely to the rotor and make all the current-supplying parts of a metal having a high electrical conductivity. As a result, the reliability of operation of the assembly is greatly improved, this being of special importance for large turbogenerators.

The present invention will further be described by way of example with reference to the accompanying drawings, wherein:

FIG. 1 represents a cross-sectional view of the winding lead assembly of the rotor of electrical machines in accordance with the present invention;

FIG. 2 is a sectional view along line lI-II of FIG. 1;

FIG. 3 is a sectional view along line III-III of FIG. I;

.FIG. 4 is an axonometric view of the assembled device;

FIG. 5 is an axonometric view of the bushing in which the rotor supply leads are fixed; and

FIG. 6 is an enlarged view of FIG. 5, showing an axonometric section of the axial and transverse slots of the bush.

It is evident from the drawings that the rotor current supply assembly comprises two insulated bars 1 and 2 arranged inside the central hole of the rotor shaft 3. Current-conducting screws 4 to 7 connect the above-mentioned bars with currentcarrying buses 8, each connected to one of the sliprings 9 or 10. Bushing I1 is fitted on the rotor shaft with the help of its end cylindrical portions resting on the seating surfaces 12 and I3 and insulated from the sliprings 9 and by means of insulating spacers l4 and 15. Keys 16 to 21 are arranged in the middle portion of the bushing 11, i.e., between the sliprings 9 and 10, using the transverse slot 22 of the bushing, and afterwards the keys to be fitted is key 23 which is fitted into position by transverse movement. The axial and transverse slots are provided on both, diametrically opposed sides of the bushing projection in accordance with the location of the screws 6-7 and bus 8 connected to one-ring 9, as well as the location of the screws 4-5 and a similar bus connected to the other slipring 10.

Key 23 is fixed on the upper supporting surfaces of the slot 22 in the bushing 11, i.e., on the bushing projections identified as a"in FIG. 6.

It is not necessary for the key 23 to rest on keys l8 and 19, a clearance b" being permitted, as shownin FIG. 4, between these keys in accordance with the assembly procedure. The

16-2], because the distance 1, between the bushing supports of the key 23 (FIG. 5) and thedistance 1, between the supports of the keys 16-21 differ insignificantly. Moreover, it the device is constructed in accordance with the accompanying drawings, the principal mechanical stresses from the screws 4-7 are taken up by the keys [6-18 and 19-21 arranged over the screws, while the key 23 takes up virtually its own centrifugal forces plus a relatively small stress from overlying insulation and a portion of the current-carrying bus 8. For safely holding the elements of the current supply assembly, the keys 16-21 and 23 are located in the axial slots, as well as in the transverse slot, of the bushing, gaskets of sufficient thickness being interposed between the keys and insulatingblocks 24.

mechanical stresses developed by centrifugal forces during rotor operation are identical on the key 23 and the other keys from the rotor shaft and bushing II. The key 16 serves to hold in place the insulation on the bus 8 at the point where it emerges from the bushing, while keys'2l and 23 are held by stops 26, the whole system of keys 16-21 and 23 in the bushing 11 being thus prevented from possible displacements likely to be'caused by vibration in operation. When hydrogen cooling is used, sealing gaskets 27 are installed between the shaft 3 and the current-conducting screws 4 to 7, the gaskets being fixed to said screws with the help of nuts 28 and on the shaft, with the help of nuts 29. This sealing prevents gas escape through the openings in the rotor shaft.

The provision for a transverse slot 22 in the bushing 11 leads to a reduction in the spacing between the sliprings to a minimum, making unnecessary special gaps between the sliprings and the projection on the bushing 11 to pennit installation of the keys 16-21 in the axial slots of the bushing.

The keys in the axial and transverse slots of the bushing fix the elements of the supply assembly, relieving the screws 4 to 7 and the buses 8 of expansion deformation during the rotor operation and making possible, for this reason, the currentconducting elements to be made of copper, 'a material possessing a relatively low mechanical strength and a high electric conductivity. Copper reduces the overheating of current-conducting elements and increases the reliability of the device, including the reliability of the sealing gaskets 27 made of rubber and installed between the screws 4-7 and the shaft 3.

What is claimed is:

l. A device for fixing the current supply assembly in a rotor of an electric machine including an excitation winding and current-conducting bars connected to the winding, said device comprising a shaft provided with slots to accommodate said' fitted on said shaft and sliprings arranged on said bushing and electrically insulated therefrom, conductive buses, current conducting screws, said sliprings being' connected via said conductive buses to said current-conducting bars by said current-conducting screws, said screws and said buses being insulated from the rotor shaft and the bushing, and keys on the bushing and located in axial and transverse slots provided in the bushing.

2. A device as claimed in claim 1 wherein each of said buses extend axially along said bushing, said buses being provided with a first portion which is interposed between said bushing and one of said sliprings, and also provided with a second portion which is interposed between said bushing and said shaft, said first and second portions being interconnected by a third portion in an opening provided in said bushing transversely of said shaft.

3. A device as claimed in claim I including a sealing gasket interposed between said shaft and each of said current conducting screws.

4. A device as claimed in claim. I wherein said axial slot and said transverse slot communicate with one another.

5. A device as claimed in claim 4 wherein said axial and transverse slots communicating with one another are provided as two pairs of slots and are provided one pair in each of two diametrically opposite portions of said bushing.

6. A device as claimed in claim 1 wherein one of said keys is provided with a shouldered portion being vertically spaced from a projected portion provided on an adjoining key.

7. A device as claimed in claim 2 including insulation provided on said third portion of one of said buses, one of said keys axially engaging and securing said insulation on said third portion.

8. A device as claimed in claim 1 wherein said axial slot is defined by two opposingly spaced axial walls provided in said bushing, each of said axial walls being provided with an axial groove, and said transverse slot is defined by two opposingly spaced circumferential'walls provided in said bushing, each of said circumferential walls being provided with a groove extending transversely of said axial grooves, atleast one of said keys being provided with shoulders adapted for seating in said axial grooves, and one of said keys being provided with shoulders adapted for seating in said grooves extending transversely of said axial grooves. 1

9. A device as claimed in claim 1 wherein said bushing is provided with a first stop engaged by one of said keys in said axial slot, and a second stop engaged by one of said keys in said transverse slot. 

1. A device for fixing the current supply assembly in a rotor of an electric machine including an excitation winding and currentconducting bars connected to the winding, said device comprising a shaft provided with slots to accommodate said excitation winding and with a central hole which encloses said currentconducting bars connected to said winding; a bushing fitted on said shaft and sliprings arranged on said bushing and electrically insulated therefrom, conductive buses, currentconducting screws, said sliprings being connected via said conductive buses to said current-conducting bars by said currentconducting screws, said screws and said buses being insulated from the rotor shaft and the bushing, and keys on the bushing and located in axial and transverse slots provided in the bushing.
 2. A device as claimed in claim 1 wherein each of said buses extend axially along said bushing, said buses being provided with a first portion which is interposed between said bushing and one of said sliprings, and also provided with a second portion which is interposed between said bushing and said shaft, said first and second portions being interconnected by a third portion in an opening provided in said bushing transversely of said shaft.
 3. A device as claimed in claim 1 including a sealing gasket interposed between said shaft and each of said current conducting screws.
 4. A device as claimed in claim 1 wherein said axial slot and said transverse slot communicate with one another.
 5. A device as claimed in claim 4 wherein said axial and transverse slots communicating with one another are provided as two pairs of slots and are provided one pair in each of two diametrically opposite portions of said bushing.
 6. A device as claimed in claim 1 wherein one of said keys is provided with a shouldered portion being vertically spaced from a projected portion provided on an adjoining key.
 7. A device as claimed in claim 2 including insulation provided on said third portion of one of said buses, one of said keys axially engaging and securing said insulation on said third portion.
 8. A device as claimed in claim 1 wherein said axial slot is defined by two opposingly spaced axial walls provided in said bushing, each of said axial walls being provided with an axial groove, and said transverse slot is defined by two opposingly spaced circumferential walls provided in said bushing, each of said circumferential walls being provided with a groove extending transversely of said axial grooves, at least one of said keys being provided with shoulders adapted for seating in said axial grooves, and one of said keys being provided with shoulders adapted for seating in said grooves extending transversely of said axial grooves.
 9. A device as claimed in claim 1 wherein said bushing is provided with a first stop engaged by one of said keys in said axial slot, and a second stop engaged by one of said keys in said transverse slot. 